Quinlan Eoin, Matthews Susan E, Gunnlaugsson Thorfinnur
School of Chemistry, Center for Synthesis and Chemical Biology, Trinity College Dublin, Dublin 2, Ireland.
J Org Chem. 2007 Sep 28;72(20):7497-503. doi: 10.1021/jo070439a. Epub 2007 Aug 29.
The synthesis and the spectroscopic studies of the amidourea based calix[4]arene sensors 1 and 2 are described. The 4-nitrophenyl based sensor 1 was synthesized in two steps from the corresponding calix [4]arene tetraethyl ester and shown to give rise to color changes in the UV-vis spectra in DMSO upon recognition of pyrophosphate and fluoride. Fitting the changes in the absorption spectra using nonlinear regression analysis indicated strong binding of several anions by 1 such as acetate and hydrogen phosphate in 1:1 (Host:Guest) stoichiometry, and at higher concentration in 1:2 stoichiometry. The preorganized calix-cavity was, however, not found to host chlorine while binding of bromide was determined. At high concentrations of these anions, significant colorimetric changes were also observed that were clearly visible to the naked eye for both pyrophosphate and fluoride. The phenyl analogue 2 was made to enable analysis of the anion recognition using 1H NMR titrations and showed that ions such as phosphate were bound in 1:1 stoichiometry, whereas the "urea" protons were shown to be significantly affected upon coordination to the anion.
本文描述了基于氨基脲的杯[4]芳烃传感器1和2的合成及光谱研究。基于4-硝基苯基的传感器1由相应的杯[4]芳烃四乙酯分两步合成，在二甲基亚砜中识别焦磷酸根和氟离子时，其紫外-可见光谱会发生颜色变化。使用非线性回归分析拟合吸收光谱的变化表明，传感器1能与多种阴离子以1:1（主体:客体）化学计量比强烈结合，如乙酸根和磷酸氢根，在较高浓度下则以1:2化学计量比结合。然而，预组织的杯状空腔未发现能容纳氯离子，但确定了其对溴离子的结合。在这些阴离子的高浓度下，还观察到显著的比色变化，焦磷酸根和氟离子的变化肉眼清晰可见。制备苯基类似物2是为了通过¹H NMR滴定分析阴离子识别情况，结果表明磷酸根等离子以1:1化学计量比结合，而“脲”质子在与阴离子配位时受到显著影响。
